Large cystic mass in the right atrium: multimodality imaging and pathologic features of a giant interatrial septal aneurysm.

The case demonstrates the use of echocardiography, cardiac computed tomography (CCT) and cardiac magnetic resonance imaging (CMRI) to determine the size, location, anatomic connection, perfusion and hemodynamic significance of a large tumor in the right atrium. The mass was surgically excised and pathology confirmed an ultimate diagnosis of an interatrial septal aneurysm (ISA). Transesophageal echocardiography enhances the sensitivity of detecting ISA and is the initial test of choice when an ISA is suspected on transthoracic echocardiography. In addition, the use of CCT and CMRI helps further define the anatomy, perfusion and tissue characteristics of the mass. Our case demonstrates the utility of multimodality non-invasive imaging to characterize an unusual tumor leading to a successful surgical treatment and a corresponding pathologic diagnosis of a large, cystic aneurysm of the interatrial septum.